Abstract: In order to study the distribution of root system of Caragana korshinskii Kom. and amino acids in different soil depths, this paper analyzed the distribution characteristics of Caragana korshinskii Kom. root system with 3 different diameter grades, and free amino acid content in different soil layers under same internal conditions in the Huanghuadianzi watershed research area of Aohan Banner, Inner Mongolia. The results showed that: ① The bone root and fine root were horizontal and vertical gradient. The root length  decreased layer by layer, but fine root distribution area was much larger than that of bone root and coarse root. The length of bone root decreased first, then increased. The overall distribution showed a peak with skewness coefficient of 0.908. The standard deviation was 34.522. The overall distribution of root system was not large and root length  evenly distributed. ②Among 17 kinds of amino acids, 4 had the highest contents. They were proline > aspartic acid > histidine > glutamic acid. Different soil depths had obvious effects on free amino acids distribution in root system of Caragana korshinskii Kom.. The law of free amino acids contents changed along with the increase of soil depth in these 4 root systems. The proline content decreased first then increased. The aspartic acid increased layer by layer. The contents of histidine and glutamic acid increased first then decreased. ③The correlation coefficient between total root length density and free amino acid content of Caragana korshinskii Kom. reached 0.944, showing a significant correlation (P>0.05). As a main channel to absorb water and nutrients, fine roots were extensively distributed in deep soil layer, being an important prerequisite to ensure normal plant growth and development. Results of this study  provided theoretical basis for rejuvenation of Caragana korshinskii Kom. in agro-pasture transition zone in Inner Mongolia; and guiding suggestions for regional vegetation restoration and ecological environment construction.

Key words: Caragana korshinskii kom., root system distribution, free amino acid, soil layer depth, agro-pasture transition zone in Inner Mongolia

摘要： 为研究柠条锦鸡儿根系及氨基酸在不同土壤深度的分布状况，在内蒙古敖汉旗黄花甸子流域研究区，在相同立地条件下分析了不同土层柠条锦鸡儿三种不同径级根系分布特征及其游离氨基酸含量。结果表明：①骨骼根和细根在水平和垂直梯度上，根长均为逐层递减，但细根分布面积远远大于骨骼根和粗根。骨骼根根长先减少后增大，总体呈偏度系数为0.908的尖峰分布，标准差为34.522，根系分布总体离散程度不大，根长分布均匀。②在17种氨基酸中，含量较大的四种氨基酸分别是：游离脯氨酸>天冬氨酸>游离组氨酸>游离谷氨酸。不同深度对柠条锦鸡儿根系游离氨基酸分布的影响较为明显，四种根系游离氨基酸随土层深度增加其含量变化规律为：脯氨酸含量先减后增，天冬氨酸逐层增大，组氨酸和谷氨酸含量先增后减。③柠条锦鸡儿根系总根长密度和游离氨基酸含量相关系数达0.944，呈显著相关（P<0.05）。细根作为吸收水分和养分的主要场所，在深土层中有较大量的分布，是确保植物正常生长发育的重要前提。此研究结果可为内蒙古农牧交错带柠条锦鸡儿复壮研究提供理论依据，为区域植被恢复和生态环境建设提供指导性建议。

关键词: 柠条锦鸡儿, 根系分布, 游离氨基酸, 土层深度, 内蒙古农牧交错带